[`pyupgrade`] Add `from __future__ import annotations` automatically (`UP006`) by 11happy · Pull Request #23260 · astral-sh/ruff

11happy · 2026-02-13T06:35:28Z

Summary

part of #19359

Test Plan

added tests & snapshots

astral-sh-bot · 2026-02-13T06:42:18Z

`ruff-ecosystem` results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

ntBre

We need to be a bit more careful here to preserve the existing behavior of both FA100 and UP006 on stable and isolate the change to preview mode. We also need to check whether or not the from __future__ import annotations fix has been enabled in the user's configuration.

ntBre · 2026-02-20T22:44:24Z

crates/ruff/tests/cli/lint.rs

+    success: false
+    exit_code: 1
    ----- stdout -----
-    All checks passed!
+    test.py:1:31: UP006 Use `list` instead of `List` for type annotation
+    Found 1 error.
+    No fixes available (1 hidden fix can be enabled with the `--unsafe-fixes` option).


I don't think this is testing what it's meant to test now, but I think I'm going to have another comment farther down about why that is.

ntBre · 2026-02-20T22:45:43Z

crates/ruff_linter/src/checkers/ast/analyze/expression.rs

-                            if checker.is_rule_enabled(Rule::FutureRewritableTypeAnnotation) {
-                                if !checker.semantic.future_annotations_or_stub()
-                                    && checker.target_version() < PythonVersion::PY39
-                                    && checker.target_version() >= PythonVersion::PY37
+                            if checker.source_type.is_stub()
+                                || checker.target_version() >= PythonVersion::PY39
+                                || (checker.target_version() >= PythonVersion::PY37
                                    && checker.semantic.in_annotation()
-                                    && !checker.settings().pyupgrade.keep_runtime_typing
-                                {
-                                    flake8_future_annotations::rules::future_rewritable_type_annotation(checker, expr);
-                                }
-                            }


We need to preserve the existing FA100 behavior for now and only make this a preview change, so we can't just delete the FutureRewritableTypeAnnotation check.

We also need to check if the future-annotations setting is enabled, otherwise UP006 shouldn't apply this fix.

What happens if FA100 is also enabled in preview? I don't think we needed to revert all changes to this code, we needed to make FA100 only fire when preview is disabled.

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

11happy · 2026-03-05T07:58:46Z

Done, I have adressed the feedback & currently converted it to preview. Thank you for having patience with this PR.
: )

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

…rules__pyupgrade__tests__UP006_future.py.snap

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

…or_UP006' into import_annotation_for_UP006

ntBre · 2026-03-05T16:45:54Z

Could you double-check the preview gate again? The ecosystem report is still showing a ton of stable changes.

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

ntBre

Thanks for your continued work on this, but I still don't think we've gotten the preview checks exactly right. We need to handle both of these cases:

preserve the behavior of both FA100 and UP006 on stable
disable FA100 in preview when the preview fix for UP006 will add the __future__ import (this includes checking future-annotations)
- the FA100 diagnostic is otherwise redundant

Along these lines, I think we should make sure that we have preview and non-preview tests covering the case where both rules are enabled.

ntBre · 2026-03-06T17:29:30Z

crates/ruff_linter/resources/test/fixtures/pyupgrade/UP006_future.py

Do we need a new test file, or could we just run one or more of the existing UP006 test fixtures with future-annotations enabled?

oh sure, I use previous one.

ntBre · 2026-03-06T17:31:55Z

crates/ruff_linter/src/checkers/ast/analyze/expression.rs

+                                            || is_up006_future_annotations_fix_enabled(
+                                                checker.settings(),
+                                            ))


Should we also check whether future-annotations is enabled here? I think we have to check it again in the rule itself, but if the setting is disabled, I don't think the preview check matters, i.e.:

Suggested change

|| is_up006_future_annotations_fix_enabled(

checker.settings(),

))

|| (is_up006_future_annotations_fix_enabled(

checker.settings(),

) && checker.settings().future_annotations))

ntBre · 2026-03-06T17:34:30Z

crates/ruff_linter/src/rules/pyupgrade/rules/use_pep585_annotation.rs

 }
+
+fn fix_applicability(checker: &Checker) -> (Applicability, Option<Edit>) {
+    if checker.target_version() >= PythonVersion::PY39 {


The two call sites this was factored out of used 3.10, not 3.9. Is that right?

I have it simplified, however this wrt the original change totally removing the FA100 hence used 39

ntBre · 2026-03-06T17:36:18Z

crates/ruff_linter/src/rules/pyupgrade/rules/use_pep585_annotation.rs

+    if checker.target_version() >= PythonVersion::PY39 {
+        return (Applicability::Safe, None);
+    }
+    if checker.settings().pyupgrade.keep_runtime_typing {


What is this check for? I don't see this in the original code. We've already checked this when deciding whether or not to apply the rule in crates/ruff_linter/src/checkers/ast/analyze/expression.rs.

I had when I removed the FA100 totaly,

ntBre · 2026-03-06T17:38:31Z

crates/ruff_linter/src/rules/pyupgrade/rules/use_pep585_annotation.rs

+                    let (applicability, future_import) = fix_applicability(checker);
+                    let mut secondary_edit = Vec::new();
+                    secondary_edit.push(import_edit);
+                    if let Some(future) = future_import {
+                        secondary_edit.push(future);
+                    }


We could probably use some iterator tricks here like:

std::iter::once(import_edit).chain(future_import)

ntBre · 2026-03-06T17:40:29Z

crates/ruff_linter/src/rules/pyupgrade/rules/use_pep585_annotation.rs

+    if checker.settings().future_annotations
+        && is_up006_future_annotations_fix_enabled(checker.settings())
+    {
+        if checker.future_annotations_or_stub() {
+            (Applicability::Safe, None)
+        } else {
+            let future_import = checker.importer().add_future_import();
+            (Applicability::Safe, Some(future_import))


I'm honestly a bit confused by this whole helper function. This doesn't seem like a natural boundary to factor out and couple the applicability and fix. This is also the only case that returns Some(fix), and I don't think the future import fix is supposed to be safe anyway because it changes the behavior of all annotations in the file.

Yes I agree, I have simplified it. & added the tests

ntBre · 2026-03-06T17:42:10Z

crates/ruff_linter/src/checkers/ast/analyze/expression.rs

-                            if checker.is_rule_enabled(Rule::FutureRewritableTypeAnnotation) {
-                                if !checker.semantic.future_annotations_or_stub()
-                                    && checker.target_version() < PythonVersion::PY39
-                                    && checker.target_version() >= PythonVersion::PY37
+                            if checker.source_type.is_stub()
+                                || checker.target_version() >= PythonVersion::PY39
+                                || (checker.target_version() >= PythonVersion::PY37
                                    && checker.semantic.in_annotation()
-                                    && !checker.settings().pyupgrade.keep_runtime_typing
-                                {
-                                    flake8_future_annotations::rules::future_rewritable_type_annotation(checker, expr);
-                                }
-                            }


What happens if FA100 is also enabled in preview? I don't think we needed to revert all changes to this code, we needed to make FA100 only fire when preview is disabled.

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

…rules__pyupgrade__tests__UP006_future.py__preview.snap

11happy · 2026-03-09T17:07:31Z

Thanks for your continued work on this, but I still don't think we've gotten the preview checks exactly right. We need to handle both of these cases:

preserve the behavior of both FA100 and UP006 on stable

disable FA100 in preview when the preview fix for UP006 will add the __future__ import (this includes checking future-annotations)

the FA100 diagnostic is otherwise redundant

Along these lines, I think we should make sure that we have preview and non-preview tests covering the case where both rules are enabled.

Thank you for the detailed feedback , I have addressed both the cases added tests accordingly & also the stable ecosystem changes are reflected as when future import is already there marking the fix safe.

ntBre · 2026-03-09T23:45:48Z

Thank you! I pushed a couple of commits addressing my remaining concerns. I'm hoping that clears up the stable ecosystem report, and then I'll take another quick look over the whole diff tomorrow.

this should fully preserve the stable behavior of a safe fix for Python versions after 3.10

ntBre · 2026-03-10T00:23:18Z

Well that's an interesting quirk of the ecosystem check. I guess we don't get any changes even in preview since the future-annotations setting is off by default. That is the correct behavior, though.

Feedback has been addressed

amyreese · 2026-03-10T22:49:12Z

The message for FA100 is super vague, but I know that's not what you're trying to fix here. 😅

ntBre · 2026-03-11T17:38:14Z

I guess it is kind of what we're trying to fix. This is a step toward getting rid of FA100 entirely! Thanks for taking a look!

11happy changed the title ~~Import annotation for up006~~ [ruff] Add import annotation for UP006 Feb 13, 2026

ntBre requested changes Feb 20, 2026

View reviewed changes

ntBre mentioned this pull request Feb 20, 2026

[ruff] add import annotations for UP007 & UP045 #23259

Open

ntBre added rule Implementing or modifying a lint rule preview Related to preview mode features labels Feb 20, 2026

11happy added 5 commits March 5, 2026 13:23

remove dependency of FA100 from UP006

fd8c383

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

update FA100 snaps

2c5ccb2

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

add snapshot

458155a

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

update a prev snap

df04058

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

make it preview

b5b53eb

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

11happy force-pushed the import_annotation_for_UP006 branch from b1a99c8 to b5b53eb Compare March 5, 2026 07:57

11happy and others added 4 commits March 5, 2026 13:32

fix preview

ffadbde

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

Delete crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__…

8463ef1

…rules__pyupgrade__tests__UP006_future.py.snap

add preview snap

2deeb20

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

Merge remote-tracking branch 'refs/remotes/origin/import_annotation_f…

b7b1f5c

…or_UP006' into import_annotation_for_UP006

11happy added 2 commits March 6, 2026 18:19

correct preview check

7a21759

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

revert prev snap

a6bd8da

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

ntBre previously requested changes Mar 6, 2026

View reviewed changes

11happy and others added 2 commits March 9, 2026 22:14

simplify

069164a

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

Delete crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__…

2d85f50

…rules__pyupgrade__tests__UP006_future.py__preview.snap

ntBre added 2 commits March 9, 2026 18:07

fixes

21b4bf1

simplify tests

de70f36

ntBre added 3 commits March 9, 2026 19:48

tidy imports

cb4b888

fix missing version check

f9a43d2

this should fully preserve the stable behavior of a safe fix for Python versions after 3.10

add preview note to docs

0bf4a22

ntBre requested a review from amyreese March 10, 2026 18:25

ntBre changed the title ~~[ruff] Add import annotation for UP006~~ [pyupgrade] Add from __future__ import annotations automatically (UP006) Mar 10, 2026

amyreese approved these changes Mar 10, 2026

View reviewed changes

ntBre merged commit 7d54068 into astral-sh:main Mar 11, 2026
43 checks passed

ntBre mentioned this pull request Mar 11, 2026

Add from __future__ import annotations in more rules #19359

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BrewTestBot mentioned this pull request Mar 12, 2026

ruff 0.15.6 Homebrew/homebrew-core#272048

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11happy commented Feb 13, 2026

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